Conventionally, in a heat exchanger for car air-conditioning system, since weight reduction is very important, a heat exchanger using aluminum flat multiport pipes as heat transfer tubes is employed. Many of them employ a system called corrugate and are configured by setting fins made of aluminum thin plate material successively undulating between the flat tubes. Moreover, partially, there also exists a structure called finned tube type, in which fins are inserted across plural flat tubes.
On the other hand, in a heat exchanger used for air-conditioning machine for home use or building use, a finned tube structure employing copper cylindrical pipes as the heat transfer tubes, in which many fins are provided to cross plural heat transfer tubes, was mainstream; however, in recent years, similar to the car air-conditioning machine, the heat exchangers of the finned tube type using the aluminum flat tubes as the heat transfer tubes are employed in some cases (for example, refer to Patent Literature 1).